1. Field of the Invention
The present invention relates to a solid state imaging device having a solid state image sensor mounted on a premolded package.
2. Description of the Prior Art
FIG. 4 is a sectional view of a conventional solid state imaging device using a premolded package (hereinafter, referred to as "package"), while FIG. 5 illustrates the process of manufacturing the solid state imaging device.
Referring to FIG. 4 and FIGS. 5 (a) to (d), the process of manufacturing a conventional solid state imaging device using the package is described below.
First, a metallic lead frame L having a specified pattern formed by etching, pressing, or other like method is sandwiched between a first upper die 12 and a lower die 13. Thereafter, in order to ensure an opening for mounting a solid state image sensor 1, a space S corresponding to the shape of a package 15 is formed by inserting a second upper die 14 into the first upper die 12 (FIG. 5 (a)).
Subsequently, a molding resin 8 composed of a thermosetting epoxy resin or the like is injected into the space S. The molding resin 8, after injection, is kept under dwell pressure for a specified time until the molding resin 8 is cured. Then, the second upper die 14 is separated from the molded package 15 and subsequently the molded package 15 is released from the first upper die 12 and the lower die 13. After this, since the molding resin 8 of the molded package 15 is not sufficiently cured at this stage, it is heated for a further specified time so that the molding resin 8 is completely cured.
Next, resin burrs (not shown) that have overflowed from the clearances of the first upper die 12, the lower die 13, and the second upper die 14 to the lead frame L, adhering to excess portions on the lead frame, are removed. Then outer leads 4 of the lead frame L are tin- or solder-plated, bent into a specified shape and cut off, thus completing a unitary package 15 (FIG. 5 (b)).
Next, the solid state image sensor 1 cut in chips is die-bonded into the opening of the package 15 through Ag paste or the like 9. Thereafter, an aluminum thin wire or gold thin wire 5 is wire-bonded between an aluminum electrode (not shown) on the solid state image sensor 1 and an inner lead 3 of the lead frame L of the molded package 15, thereby ensuring electrical conduction to each other (FIG. 5 (c)).
Next, with a view to protecting the solid state image sensor 1 from moisture, contaminations, and others outside the molded package 15, and also to receiving rays of light converged by the lens of a video camera or the like, a transparent lid 11 made of glass or the like is attached to the molded package 15 with adhesive 10 composed of epoxy resin or the like (FIG. 5 (d)).
The above-described solid state imaging device packaged on a premolded package, when mounted on video equipment such as video cameras, encounters the following problems.
To make up a video camera or the like, it is necessary to also mount a peripheral IC (integrated circuit) for use in a solid state imaging device (hereinafter, referred to as "peripheral IC") on the video equipment. However, if the solid state image sensor and the peripheral IC are packaged on different packages, as has been the conventional case, their occupying area on a packaging substrate should necessarily be increased by their independence so that the recent years' demand for miniaturizing video cameras and other equipment could not be met satisfactorily.